Machine and track assembly for use therewith

ABSTRACT

A track assembly for a machine includes a track having inner track seals, a rotatable track engaging element such as an idler or drive sprocket and a contact interface for protecting the seals during guiding the track about the rotatable element. The contact interface may include sacrificial wear material on the rotatable element and sacrificial wear material on corresponding track links. The contact interface may have a configuration based on a location of the seals, and is adapted to inhibit wear of the track links in regions adjacent the seals. In another aspect, the contact interface is a guide interface.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a continuation of U.S. patent application Ser. No. 11/975,206, filed Oct. 18, 2007.

TECHNICAL FIELD

The present disclosure relates generally to machine track, and relates more particularly to a machine and associated track assembly having a unique interface design between track assembly components to protect inboard track seals from damage.

BACKGROUND

A wide variety of machines utilize tracks, commonly as ground engaging propulsion elements, but also for other purposes such as torque transmission and conveying. It is common for such tracks to include a plurality of rotatable track engaging elements, with the track forming an endless chain that is moved about the rotating elements during operation. The demands placed upon such machines and their associated track assemblies can be quite substantial, and machine tracks are often relatively robust to provide a long operating life despite significant mechanical stresses, strain and wear experienced during operation.

One conventional track system known from track-type tractors and the like utilizes one or more rotatable idlers which engage the tracks, typically working in conjunction with a drive sprocket. The idlers passively rotate to guide the associated track about a desired path. It is common in conventional track systems for the rotatable idler to roll against “rails” located on links of the track chains. More recently, designs have been implemented in certain machines where the rotatable idler and track are configured such that the idler contacts the track between adjacent parallel track chain assemblies, rather than riding on the rails.

One such design is known from U.S. Pat. No. 5,829,849 to Lawson. In the Lawson strategy, an idler contacts roller bushings located between track chain assemblies to support and guide the track as it rotates to propel the machine. Tapered side portions of the idler provide lateral guiding of the track chain assemblies. Lawson overcomes certain design and operating issues associated with conventional systems where the idler rides on rails. While Lawson provides a successful strategy, there is always room for improvement, particularly with regard to the wear characteristics of the system.

The present disclosure is directed to one or more of the problems or shortcomings set forth above.

SUMMARY

In one aspect, a track assembly for a machine includes a track having a first chain assembly, a second chain assembly coupled with the first chain assembly via a track pin, and a first and second seal located within a first and second bore, respectively, of track links of the first and second chain assemblies. The track assembly further includes a rotatable track engaging element configured to guide the track at least in part by contacting the track between the chain assemblies, and a contact interface between the rotatable track engaging element and the track. The contact interface includes means, located on at least one of the track and the rotatable track engaging element, for inhibiting track link wear in regions adjacent the seals during contacting the track with the rotatable track engaging element.

In another aspect, a machine includes a frame, and at least one track coupled with the frame which includes a first chain assembly and a second chain assembly, the chain assemblies each including a plurality of track links and being coupled together via a plurality of track pins. A plurality of seals are positioned within bores in the track links, and the machine further includes a rotatable track engaging element having an outer diameter contacting the track between the first chain assembly and the second chain assembly. The machine further includes a contact interface between the rotatable track engaging element and the track which includes a contact element on at least one of the track and the rotatable track engaging element which is configured to inhibit track link wear in regions adjacent to the seals during contacting the track with the rotatable track engaging element.

In still another aspect, a method of protecting seals of a machine track during operating the machine track includes the steps of moving a machine track having first and second parallel chain assemblies of track links about a rotatable track engaging element, and guiding the machine track relative to the track engaging element at least in part by contacting the track engaging element with the track between the first and second chain assemblies. The method further includes a step of, during guiding the machine track, protecting inner track seals disposed within the track links at least in part by inhibiting contact between the rotatable track engaging element and regions of the track links adjacent the inner track seals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side diagrammatic view of a portion of a machine according to one embodiment;

FIG. 2 is a side elevational view of an idler according to one embodiment;

FIG. 3 is a sectioned view taken along line 3-3 of FIG. 1;

FIG. 4 is a sectioned view taken along line 4-4 of FIG. 1;

FIG. 5 is a partial sectioned view taken along line 5-5 of FIG. 1;

FIG. 6 is a partial sectioned view of a track assembly according to one embodiment;

FIG. 7 is a partial sectioned view of the track assembly of FIG. 6 taken in a different section plane;

FIG. 8 is a partial sectioned view of a track assembly according to one embodiment;

FIG. 9 is a diagrammatic view of a portion of a track assembly according to one embodiment;

FIG. 10 is a partial sectioned view of a track assembly according to one embodiment;

FIG. 11 is a partial sectioned view of a track assembly according to one embodiment; and

FIG. 12 is a partial sectioned view of a track assembly according to one embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a portion of a machine 10 according to the present disclosure. Machine 10 is shown in the context of a track-type machine having a first ground engaging track 16, mounted at a first side of a frame 12, and also including a second ground engaging track identical to track 16 and positioned at a second side of frame 12 but not visible in FIG. 1. Track 16 extends about a plurality of rotatable track engaging elements, including an idler 20 having an axis of rotation A, a drive sprocket 68 having an axis of rotation B and a plurality of track rollers, one of which is shown and identified via reference numeral 26. Machine 10 may also include other rotatable track engaging elements coupled with each of its one or more tracks such as an additional idler. While only a single track is shown in FIG. 1, the present description of track 16 and the track assembly 14 of which it is a part should be understood to refer also to a second track and associated track assembly of machine 10. While machine 10 may be a track-type machine such as a track loader, excavator, tractor or another mobile machine, the present disclosure is not thereby limited. In other embodiments, track assembly 14 might comprise a portion of a machine such as a conveyor. In all embodiments contemplated herein, track assembly 14 will be configured such that certain types of wear, in particular wear affecting track seals as described hereinbelow, will be reduced or eliminated as compared with conventional designs.

Track 16 will typically comprise two parallel track chain assemblies, one of which is shown in FIG. 1 and identified with reference numeral 18 b, extending in parallel and coupled together via a plurality of track pins 28. In the illustrated embodiment, track chain assembly 18 b consists of a plurality of straight outboard track links 22 alternating with a plurality of straight inboard track links 24, although other track configurations such as those having S-shaped links or multi-piece link assemblies are contemplated herein.

During moving track 16 about idler 20, inboard links 24 may intermittently or continuously contact idler 20, guiding track 16 thereabout. Each inboard link 24 may have a contact length L with idler 20, the significance of which will be apparent from the following description. Links 24 will also tend to contact sprocket 68 during moving track 16 thereabout, and the present description emphasizing idler 20 should be understood to be similarly applicable to an interaction between sprocket 68 and track 16, except as otherwise indicated. Referring also to FIG. 2, there is shown a side view of idler 20 showing axis of rotation A, an outer diameter 34 or outer diameter surface, which is positioned at a constant radial distance from axis A, and an inner diameter 95 or inner diameter surface. In the embodiment shown, outer diameter 34 is configured to contact track 16 between its respective chain assemblies, in particular contacting track pins 28, or rotating bushings positioned on track pins 28, as further described herein. In other embodiments, a different engagement strategy between track 16 and idler 20 might be used, for example, a sprocketed idler could be used. Idler 20 further includes a step 32 spaced radially inwardly of outer diameter 34 and separated from outer diameter 34 via a transition surface 33 which is an outboard surface. Transition surface 33 extends a first radial distance from a seal protecting wear surface 43 b to outer diameter 34. An inboard surface 97 extends a second, greater radial distance from seal protecting wear surface 43 b to inner diameter 95. In connection with idler 20, the terms “inboard” and “outboard” mean, respectively, toward inner diameter 95 and away from outer diameter 34, and toward outer diameter 34 and away from inner diameter 95. Step 32 extends/protrudes axially from an axial side 30 of idler 20, axial side 30 extending in a radial direction from inner diameter 95 to outer diameter 34. Step 32 assists in mitigating wear in track assembly 14 during operation, as further described herein. It may further be noted from FIG. 2 that step 32 includes concentric radially inward and radially outward step edges 103 and 101, respectively, which each define a circle centered on axis A, and that transition surface 33 adjoins outer diameter 34 at a corner 100. An opposite axial side of idler 20 is not visible in FIG. 2, but will typically be substantially identical to axial side 30.

Referring now to FIG. 3, there is shown a sectioned view taken along line 3-3 of FIG. 1. As illustrated in FIG. 3, outer diameter 34 of idler 20 contacts a rotating bushing 25 positioned about pin 28. In the illustrated embodiment, pin 28 comprises a cartridge pin having a fluid cavity 39 sealed via a plug 47. Pin 28 may further include inboard collars 50 positioned on opposite sides of rotating bushing 25, and outboard collars 52 positioned outboard of each inboard collar 50, and coupled with pin 28 via any suitable means such as snap rings or the like. In other embodiments, a pin configuration or a pin assembly different from that illustrated in FIG. 3 might be used, such as a pin having an integral bushing, or a pin assembly other than a cartridge pin. Track chain assembly 18 b, including an inboard link 24 b and an outboard link 22 b is positioned on pin 28, as is another track chain assembly 18 a, also including an inboard link 24 a and an outboard link 22 a. Each of inboard links 24 a and 24 b includes a bore 46 a and 46 b, respectively, which is typically press fit with inboard collars 50. A first inner track seal 54 a and a second inner track seal 54 b are positioned within collars 50, and thus positioned within bores 46 a and 46 b, respectively. Exposed seal regions 105 of links 24 a and 24 b face a track guiding space 107. Lubricating fluid from cavity 39 may be distributed to various of the components of track 16, and fluidly sealed from escaping via seals 54 a and 54 b, and such other seals as may be used in conjunction with outboard collars 52. Each of track chain assemblies 18 a and 18 b may further include a rail 23 upon which other rotatable track engaging elements such as track roller 26 ride during operation.

It has been discovered that in certain conventional track assembly designs, rotatable components such as idlers and drive sprockets can have a tendency to wear away material from inboard track links, eventually exposing and damaging inboard track seals and causing leaks of lubricating fluid, as well as potentially damaging the track. This phenomenon tends to result at least in part from the shape of the track assembly components in regions where they have a tendency to contact one another. The present disclosure provides unique strategies for inhibiting this type of wear, and in particular includes a first contact interface 40 a and a second contact interface 40 b, which inhibit track link wear in regions of the track links adjacent seals 54 a and 54 b.

In one embodiment, seals 54 a and 54 b may be protected from wear-related damage at least in part by placing seals 54 a and 54 b within recesses 60 of contact interfaces 40 a and 40 b. It may be noted from FIG. 3 that ends of roller bushing 25 extend into recesses 60 in links 24 a and 24 b. The illustrated configuration can assist in inhibiting wear of regions of track links 24 a and 24 b adjacent seals 54 a and 54 b, respectively, by positioning seals 54 a and 54 b relatively further from idler 20. It should be appreciated that over the course of many hours of operation, components such as bushing 25 can wear away, such that idler 20 can actually migrate closer to seals 54 a and 54 b than that which is shown in FIG. 3. Recessing seals 54 a and 54 b can prevent or delay a time at which idler 20 wears material of links 24 a and 24 b and begins to impinge on seals 54 a and 54 b. Moreover, in some embodiments using recesses 60 to protect seals 54 a and 54 b may be the sole means for inhibiting track link wear in regions adjacent thereto, whereas in other embodiments recesses 60 might be used in conjunction with other means for inhibiting track link wear, or might not be used at all.

In certain embodiments, with or without using recesses 60, contact interfaces 40 a and 40 b may be understood as “wear” interfaces which direct wear between element 20 and chain assemblies 18 a and 18 b predominantly to areas of links 24 a, 24 b other than regions adjacent track seals 54 a and 54 b. For example, regions of track links 24 a and 24 b where recesses 60 are disposed in the FIG. 3 version may be understood as “adjacent to” seals 54 a and 54 b as the term “adjacent to” is intended to be understood herein. In other embodiments, described hereinbelow, contact interfaces of a track assembly may comprise guide interfaces, which, rather than directing wear, inhibit or limit certain types of contact between the respective components in the first place. By designing track assembly 14 in the manner described herein, wear on inboard track links 24 a and 24 b in regions adjacent seals 54 a and 54 b, respectively, can be reduced or eliminated as compared with conventional designs. In one embodiment, each contact interface 40 a and 40 b may include sacrificial wear material 42 a and 42 b, respectively, located on idler 20, as well as sacrificial wear material 44 a and 44 b located on inboard track links 24 a and 24 b, respectively. In other embodiments, sacrificial wear material might be located on only one of track 16 and element 20. As mentioned above, idler 20 may include a step 32 b on a first axial side 30, and another step 32 a on an opposite axial side 31, comprising portions of contact interfaces 40 a and 40 b. Each of steps 32 a and 32 b may protrude in axial directions relative to sides 31 and 30, respectively, and be spaced radially inwardly of outer diameter 34.

In one embodiment, each of contact interfaces 40 a and 40 b may comprise a first planar face 43 a and a second planar face 43 b located on steps 32 a and 32 b, respectively, each of which comprises a seal protecting wear surface also identified via reference numerals 43 a and 43 b, and including wear material 42 a and 42 b. Contact interfaces 40 a and 40 b may also include a third planar face 45 a and a fourth planar face 45 b located on track links 24 a and 24 b and including sacrificial wear material 44 a and 44 b, respectively. Planar faces 43 a, 43 b, 45 a and 45 b may be oriented perpendicular axis A of idler 20 such that a contact length L between links 24 a and 24 b and idler 20 comprises a planar interface. The respective planar faces of the wear interfaces may face toward one another, in opposed directions, at all locations where idler 20 and links 24 a and 24 b may come into contact during operation, and may be parallel. This configuration can eliminate or reduce contact between edges or corners of idler 20 and portions of links 24 a and 24 b, as may occur where an idler having tapered axial surfaces is used. In other embodiments, certain of which are described herein, non-planar faces of wear material may be used.

In one embodiment, wear material 42 a and 42 b and wear material 44 a and 44 b may consist of hardened forged or cast material of idler 20 and inboard track links 24 a and 24 b, respectively. Wear material 42 a, 42 b, 44 a and 44 b may consist of the forged material of the respective components which is hardened by heat treating. In other embodiments, induction hardening, coatings or some other hardening strategy might be used. In FIG. 3, reference numeral 45 identifies forged material of inboard track links 24 a and 24 b. It will often, though not necessarily, be desirable to avoid hardening material of inboard track links 24 a and 24 b in regions where bores 46 a and 46 b are located, to avoid interfering with press fits with inboard inserts 50. To this end, unhardened material 45 of each link 24 a and 24 b may define bores 46 a and 46 b.

Turning now to FIG. 5, there is shown a partial sectioned view taken along line 5-5 of FIG. 1. As mentioned above, drive sprocket 68 may have a configuration having certain similarities with that of idler 20 to address similar wear concerns with respect to track 16. Sprocket 68 may include a plurality of outer track contacting segments 70, one of which is shown, each including a plurality of teeth 72 alternating with a plurality of pockets 74. It should be appreciated that in the FIG. 5 illustration, tooth 72 is positioned forwardly of the section plane and is therefore shown in phantom. It may also be noted from FIG. 5 that pocket 74 engages with rotating bushing 25 between the respective track chain assemblies.

A first contact interface 140 a and a second contact interface 140 b may be positioned on opposite axial sides of sprocket 68, and each may include wear material 80 a and 80 b located on sprocket 68 and wear material 44 a and 44 b located on inboard track links 24 a and 24 b. Interfaces 140 a and 140 b may each have a configuration based at least in part on a location of seals 54 a and 54 b within their corresponding track links, similar to wear interfaces 40 a and 40 b associated with idler 20. In other words, by providing a particular shape for the interfacing components, based on a location of the seals to be protected, wear can predominantly occur in regions not adjacent to the subject seals. For instance, in the case of sprocket 68 and idler 20, they are each configured via wear interfaces having wear material of an appropriate shape and location such that material is worn away from links 24 a and 24 b predominantly in regions relatively closer to rails 23, avoiding wear relatively closer to seals 54 a and 54 b.

“Guide” interfaces, as further described herein, may also be used in connection with sprocket 68, rather than the illustrated wear features. In one embodiment, sprocket 68 may include a hub portion 76 having track contacting segment 70 coupled therewith via a plurality of bolts 82. In other embodiments, rather than plural track contacting segments, sprocket 68 might consist of a single cast or forged piece, or one track contacting portion coupled with a separate hub portion. A nut strip 78 or the like may be provided which receives a threaded end of each of bolts 82. In FIG. 5, nut strip 78 is shown diagrammatically as a single piece, but may include a plurality of segments corresponding to a plurality of track contacting segments 70. In one embodiment, wear material 80 a may be positioned on nut strip 78, at a first axial side of sprocket 68, whereas other wear material 80 b may be positioned on an opposite axial side of sprocket 68, comprising a portion of segment 70. It will be noted that the configuration of nut strip 78 and segment 70 is at least generally analogous to steps 32 a and 32 b of idler 20, each of elements 78 and 70 having a planar face 143 a and 143 b which comprises a portion of the corresponding contact interface 140 a and 140 b, respectively.

Turning now to FIG. 6, there is shown a track assembly 214 according to yet another embodiment. Track assembly 214 includes a rotatable track engaging element 220, such as an idler, having a first axial side 231 and a second axial side 230. Rotatable track engaging element 220 is configured to contact a track 216 between a first track chain assembly 218 a and a second track chain assembly 218 b. Track assembly 214 further includes a first contact interface 240 a between element 220 and chain assembly 218 a, and a second contact interface 240 b between element 220 and track chain assembly 218 b. Contact interfaces 240 a and 240 b may include a first step 232 a and a second step 232 b, respectively, positioned to extend from first and second axial sides 231 and 230 and spaced radially inward of an outer diameter 234 of element 220, and each including sacrificial wear material thereon. The embodiment shown in FIG. 6 has certain similarities with previously described embodiments, in that contact interfaces 240 a and 240 b may comprise wear interfaces whereby damage to inner track seals 54 a and 54 b is inhibited via the proper placement of wear material, having an appropriate shape, which is based at least in part on a location of track seals 54 a and 54 b within their corresponding track links. In other words, like the embodiment of FIG. 3 the embodiment shown in FIG. 6 can include sacrificial wear material which wears away as track chain assemblies 218 a and 218 b are moved about element 220, avoiding wear in regions of the corresponding track links adjacent track seals 54 a and 54 b. In one embodiment, each of steps 232 a and 232 b may have a conical face 243 a and 243 b, respectively, which includes sacrificial wear material, whereas each of the inboard track links 224 may include an opposed face 245 a and 245 b, respectively, which is configured to contact faces 243 a and 243 b, respectively, during operation of track assembly 214.

Track assembly 214 differs from track assembly 14 described above in that, rather than each contact interface including an interface of planar surfaces, faces 243 a and 243 b may be conical, and disposed at an angle relative to an axis of rotation of element 220, rather than being perpendicular thereto as in track assembly 14. Faces 245 a and 245 b may be conical, planar or some other configuration. Referring also to FIG. 7, there is shown a sectioned view of track assembly 214 taken in a different section plane, at a location spaced from pin 28 in contrast to FIG. 6 which is sectioned approximately through the middle of pin 28.

Referring now to FIG. 8, there is shown another track assembly 314. It should be appreciated that track assembly 314 might be used with or comprise a part of one of the other track assemblies described herein, and is thus not necessarily a separate system. Track assembly 314 may include a rotatable track engaging element 368, such as a drive sprocket, having a flange 376 which is coupled with at least one track contacting segment 370 having alternating teeth 372 and pockets 374. Sprocket 368 operates generally in a manner similar to that described above with regard to the embodiment of FIG. 5, but has certain differences. Sprocket 368 is configured to engage with a track having a first track chain assembly 318 a and a second track chain assembly 318 b, and contacts the corresponding track between chain assemblies 318 a and 318 b, track contact segment 370 functioning in a manner similar to that of the embodiment of FIG. 5 to apply driving force to the associated track. A nut strip 378 may be bolted to flange 376, and in certain embodiments could include a plurality of separate nut strips. Nut strip 378 comprises a portion of a contact interface 340 between drive sprocket 368 and chain assemblies 318 a and 318 b. In contrast to the embodiment of FIG. 5, nut strip 378 may include a conical face 343 which is configured to contact another face 345 on links of chain assembly 318 b. An additional contact interface having a configuration similar to that of interface 340, to protect seals within track chain assembly 318 a, might be located on a side of sprocket 368 opposite that of interface 340 in certain embodiments.

Referring to FIG. 9, there is shown a diagrammatic view of a track contacting segment 470 suitable for use with a track engaging element such as a toothed idler or drive sprocket. Track contacting segment 470 may include an arcuate body 471 having a plurality of teeth 472 alternating with pockets 474, and is configured to engage with a track in a conventional manner. Arcuate body 471 further includes an outer diameter surface 434, an inner diameter surface 413 defining a segment of a circle C having a center axis Z, a first axial side 430, a second axial side 431, and a plurality of apertures 440 communicating between axial sides 430 and 431. An Outboard axial surface 433 is shown located on axial side 430 in FIG. 9. Track contacting segment 470 further includes a contact interface 440 which comprises a discontinuous contact interface wherein faces of wear material 432 are spaced apart rather than consisting of a continuous step or the like. Identical wear material faces 432 may be located upon axially projecting steps 439, and spaces apart in an arcuate configuration as shown. The spacing between the faces of wear material 432 may be used to access bolts, etc. received in apertures 440 for coupling segment 470 with a hub component, etc. as will be readily apparent to those of skill in the art.

Referring now to FIG. 10, there is shown a sectioned view of yet another track assembly 514. Track assembly 514 may include a rotatable track engaging element 520, such as an idler or possibly a drive sprocket, configured to engage with a track having a first chain assembly 518 a and a second chain assembly 518 b, each of which includes a plurality of inner track seals 54 a and 54 b. Track assembly 514 is an example of a track assembly according to the present disclosure wherein rather than a contact interface which comprises a wear interface to direct wear between the respective components, the contact interface 540 of track assembly 514 comprises a guide interface wherein contact between rotatable track engaging element 520 and track links of chain assemblies 518 a and 518 b is inhibited or avoided altogether, to protect inner track seals 54 a and 54 b. Any of the “guide” interface embodiments described herein might be used also with “wear” interfaces if desired. In one embodiment, contact interface 540 may include a first guide element 534 on rotatable track engaging element 520, and a second guide element 535 complementary to guide element 534 which is located on a roller bushing 525. In the embodiment shown, track engaging element 520 includes a crown 534 which fits within a complementary groove 535 formed in roller bushing 525. Accordingly, during operation of track assembly 514 rotatable track engaging element 520 and track chain assemblies 518 a and 518 b are maintained in a state at which contact between axial sides or corners of track engaging element 520 and inboard track links 524 is limited or avoided, as interaction between crown 534 and element 535 tends to keep element 520 from moving laterally toward either of chain assemblies 518 a and 518 b. In a related embodiment, the configuration of the components of contact interface 540 might be reversed. In other words, roller bushing 525 could include a crown, and track engaging element 520 could include a groove.

Turning to FIG. 11, there is shown yet another track assembly 614 according to the present disclosure. Similar to the embodiment shown in FIG. 10, track assembly 614 includes a contact interface 640 wherein, rather than directing wear between components, wear is avoided by inhibiting or eliminating contact between certain of the components. In particular, a rotatable track engaging element 620 is provided which includes a tab or ridge 636 formed on an outer diameter 634 thereof. Tab 636 will typically be circumferential of outer diameter 634 and may fit within a slot 635 formed in a roller bushing 625, such that side to side movement of element 620 relative to a first track chain 618 a and a second track chain 618 b is limited, reducing or eliminating a tendency for rotatable track engaging element 620 to contact inner track links 624 in regions adjacent inner track seals 54 a and 54 b. Contact interface 640 might also be reversed, such that slot 635 is in element 620 and tab 636 is formed on roller bushing 625.

Turning now to FIG. 12, there is shown still another track assembly 714 according to the present disclosure. Track assembly 714 also includes a rotatable track engaging element 720 having an outer diameter 734. Outer diameter 734 contacts a roller bushing 725 positioned between a first chain assembly 718 a and a second chain assembly 718 b. Track assembly 714 further includes contact interfaces 740 a and 740 b. In the embodiment shown in FIG. 12, each of contact interfaces 740 a and 740 b includes a flange 726 a and 726 b located at each end of roller bushing 725. During operation, flanges 726 a and 726 b may inhibit or eliminate contact between track engaging elements 720 and inboard track links 724 in regions where track seals 54 a and 54 b are located, as flanges 726 a and 726 b are positioned inboard of track seals 54 a and 54 b and between links 724 and element 720. Flanges 726 a and 726 b could also comprise sacrificial wear material, such as hardened material, which wears away via contact with element 720.

Industrial Applicability

Referring to FIGS. 1-5, the portions of contact interfaces 40 a and 40 b located on idler 20, e.g. steps 32 a and 32 b and the corresponding wear material 42 a and 42 b, are generally uniform about idler 20, having a generally circular configuration and extending inwardly from outer diameter 34, curving into and out of the page in the FIG. 3 illustration. The portions of wear interfaces 140 a and 140 b located on sprocket 68 may have an analogous configuration. The following description of idler 20 in conjunction with track 16 may thus be understood to refer to sprocket 68, except where otherwise noted. The portions of contact interfaces 40 a and 40 b located on links 24 a and 24 b and the corresponding wear material 44 a and 44 b generally have a linear configuration, extending perpendicular to and in and out of the page in FIG. 3. As a result, the interface between wear material 42 a and 42 b on idler 20 and wear material 44 a and 44 b is different at different locations along the contact length L, given the interface of a curving component, idler 20, with straight links 24 a and 24 b.

FIG. 3 illustrates the relative location of the respective planar faces of each wear interface 40 a and 40 b at one location along contact length L, i.e. at pin 28. Referring to FIG. 4, there is shown a partially sectioned view taken along line 4-4 of FIG. 1. FIG. 4 illustrates the differing relative locations of faces 45 a and 43 a, and 45 b and 43 b at a location spaced from pin 28 along contact length L. This configuration differs from that of certain earlier designs wherein at certain points along a contact length between track links and an idler, corners of the idler impinged upon surfaces of the track links in regions adjacent the track seals. As a consequence, the sharp idler corners had a certain tendency to wear away link material more quickly than desired, at least in certain instances. The present disclosure overcomes such wear issues by providing a different type of contact interface altogether, with hardened material placed in different locations and having a different shape than that of earlier strategies. It may also be noted from FIGS. 3 and 4 that surface 97 and a counterpart surface 49 on axial side 31 each include a lower axial elevation and a lower material hardness, surface 33 and a counterpart surface 35 on axial side 31 each include a middle axial elevation and a higher material hardness, and surfaces 43 a and 43 b each include a higher axial elevation and a higher material hardness. Idler 20 also includes a lesser axial thickness between surfaces 97 and 49, a medium axial thickness between surfaces 33 and 35, and a greater axial thickness between surfaces 43 a and 43 b.

It should be appreciated that idler 20 will typically have an axial thickness between planer faces 43 a and 43 b which is slightly less than a distance between planer faces 45 a and 45 b. As a result, idler 20 may alternately contact links 24 a and 24 b during moving track 16 into engagement with, rotating about, and disengaging from idler 20, the alternating contact serving to guide track 16 laterally with respect to idler 20. In other words, track 16 may move back and forth relative to idler 20, resulting in alternate contact therebetween at contact interfaces 40 a and 40 b. Relative movement of links 24 a and 24 b as the subject portion of track 16 moves into engagement with idler 20 can also result in sliding contact at contact interfaces 40 a and 40 b as outer diameter 34 moves toward or away from bushing 25 during engagement or disengagement, respectively, of a given portion of track 16 with idler 20. Each of these types of contact between the respective faces of wear interfaces 40 a and 40 b can, and is intended to, wear away wear material 42 a and 42 b and 44 a and 44 b. Outer diameter 34 will also wear due to its engagement with bushing 25, often increasing the total contact area at interfaces 40 a and 40 b as steps 32 a and 32 b migrate relatively closer to outer diameter 34 due to loss of material from outer diameter 34. In the case of sprocket 68, wear will take place in an analogous manner, simultaneously wearing material 44 a and 44 b from links 24 a and 24 b, and wearing material 80 a and 80 b from sprocket 68.

Returning to FIG. 5, it may further be noted that bushing 25 extends into recess 60. An end of bushing 25 within recess 60 of inboard track link 24 a lies in a plane A. Plane A also extends approximately along/through an inboard edge of seal 54 a. Plane A is spaced from another plane O positioned inboard of plane A. The terms “inboard” and “outboard” as used herein in describing planes A and O will be understood to have meanings familiar to those skilled in the art of machine track, i.e. inboard means toward a center of track 16 between its track chain assemblies, in other words toward a longitudinal midpoint of pin 28, whereas outboard means away from the center of track 16 and toward lateral sides of track 16, in other words toward terminal ends of pin 28. Plane O lies approximately at an outboard end of recess 60, and is in turn spaced inboard from yet another plane B which is defined by planar face 45 a. Planar face 143 a of nut strip 78 also defines a plane, plane C, which is spaced slightly inboard of plane B but will typically move relative thereto with side to side motion of sprocket 68 between track chain assemblies 18 a and 18 b. FIG. 5 illustrates certain of the design attributes of the present disclosure via the illustration of planes A, B, C and O whereby seals 54 a and 54 b, of each of the inboard links 24 a and 24 b of track 16 can be protected from wear during track operation. It should be appreciated that idler 20 has analogous features and wear characteristics with regard to protecting seals 54 a and 54 b, as its interaction with track 16 will be similar to the interaction of sprocket 68 therewith. In other words, the present description of planes A, B, C and O may be understood to refer to corresponding features of idler 20.

The separation of plane A from plane O, and the separation of plane O from plane B positions seal 54 a sufficiently away from wear interface 140 a that any tendency for sprocket 68 to wear away link material in a region of link 24 a adjacent seal 54 a is much reduced or eliminated as compared with earlier designs. In other words, for link 24 a to begin to wear adjacent seal 54 a, hardened wear material 44 a would need to be worn away such that planes B and O are no longer separated. Then, additional material would need to be worn away such that planes O and A are no longer separated. The relative distances separating the respective planes may be chosen such that seal service life is not a limiting factor in track service life. The shape of the components defining the wear interfaces described herein further reduces the wear rates as compared with earlier designs, as planar wear interfaces 40 a, 40 b, 140 a, and 140 b may wear more slowly than interfaces wherein angled, or otherwise non-planar interfaces between components are used. Moreover, hardened material abuts and wears against hardened material at the wear interfaces, in contrast to earlier strategies wherein unhardened material was subjected to wear.

In view of the foregoing, it will be appreciated that the unique configuration, location and composition of contact interfaces 40 a, 40 b, 140 a and 140 b ensures that wearing of idler 20, sprocket 68 and track links 24 a and 24 b occurs in a manner that protects seals 54 a and 54 b. In other words, by selecting an appropriate shape for the relevant parts of idler 20, sprocket 68 and links 24 a and 24 b, wear of links 24 a and 24 b will predominantly take place in regions not adjacent to seals 54 a and 54 b. Rather, links 24 a and 24 b will have a tendency to wear at planar faces 45 a and 45 b. This strategy contrasts with earlier designs, discussed above, wherein contact interfaces between the respective components had neither a shape nor other attributes that specifically accounted for the location of the inboard track seals, and consequently wear of inboard track links from contact with other track components had a tendency to take place in regions close to the inboard track seals, ultimately risking or causing seal damage and leakage.

The embodiments of FIGS. 6 and 7 will have a tendency to operate in a manner similar to that described with regard to the embodiments of FIGS. 1-5. In some instances, the embodiment of FIGS. 6 and 7 will be well suited to use with existing track configurations, except for relatively minor differences. In other words, the configuration of rotatable track engaging element 220 is such that it may be used with track chain assemblies having components sized and shaped similar to that of existing designs, without the need for reconfiguring link shape, length, etc. The embodiment shown in FIG. 8 has similar applicability to certain existing track designs. With regard to the FIG. 9 embodiment, it too will operate similarly to that of the embodiments of FIGS. 1-5, however, rather than wear occurring along a continuous contact interface, other intermittently spaced elements of contact interface 440 will wear during track assembly operation.

As discussed above, each of the embodiments of FIGS. 10 and 11 may rely at least in part upon guiding between the rotatable track engaging element 520, 620, and the associated track chain assemblies 518 a and 518 b, and 618 a and 618 b, respectively. In other words, rather than directing wear to particular regions of the track links, contact between the respective components is limited in the first place. The embodiment of FIG. 12 can function to protect track seals 54 a and 54 b in a manner that relies upon both guiding between the components and sacrificial wear material. In one embodiment, flanges 726 a and 726 b may include sacrificial wear material, and rotatable track engaging element 720 may also include sacrificial wear material in corresponding locations. During operation of track assembly 714, wear between flanges 726 a and 726 b and element 720 can prevent wear of inboard track links 724 in regions adjacent seals 54 a and 54 b. In addition, flanges 726 a and 726 b may assist in guiding element 720 to reduce or eliminate the tendency for element 720 to contact links 724.

The present disclosure thus provides a number of different ways of addressing certain wear issues in track assemblies. It should be appreciated that many of the features of the various embodiments could be combined in a single track assembly. Moreover, many of the specific features disclosed herein might be omitted from a track assembly design without departing from the scope of the present disclosure. It should further be appreciated that the specific geometry of the various contact interface designs might be changed substantially. For example, rather than steps 32 a and 32 b having the illustrated configuration, they might have a rounded shape. Further still, the shapes of, and interaction between, components may vary over time as material is worn away, while still providing protection for seals 54 a and 54 b.

The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. 

1. A rotatable track engaging idler, for guiding a ground engaging track having first and second chain assemblies including track pins received in bores formed in inboard track links, bushings positioned on the track pins, and inner track seals positioned in the bores and being adjacent to exposed seal regions of the inboard track links facing a track guiding space, the rotatable track engaging idler comprising: an idler body defining an axis of rotation and including an inner diameter surface, an outer diameter surface positioned at a constant radial distance from the axis of rotation, and first and second axial sides extending in a radial direction from the inner diameter surface to the outer diameter surface, the idler body further having a contact interface including seal protecting wear surfaces positioned on each of the axial sides; each of the axial sides includes an outboard surface extending a first radial distance from the corresponding seal protecting wear surface to the outer diameter surface, and an inboard surface extending a second, greater radial distance from the corresponding seal protecting wear surface to the inner diameter surface; and wherein each of the inboard surfaces includes a lower axial elevation and a lower material hardness, each of the outboard surfaces includes a middle axial elevation and a higher material hardness, and each of the seal protecting wear surfaces includes a higher axial elevation and a higher material hardness, whereby the contact interface directs contact between the idler body and the inboard track links away from the exposed seal regions and limits a wear rate of the seal protecting wear surfaces in response to contacting the inboard track links.
 2. The rotatable track engaging idler of claim 1 wherein each of the seal protecting wear surfaces includes a continuous annular configuration about the idler body.
 3. The rotatable track engaging idler of claim 2 wherein the contact interface includes axially projecting steps whereupon the seal protecting wear surfaces are located.
 4. The rotatable track engaging idler of claim 3 wherein each of the seal protecting wear surfaces includes a planar face oriented perpendicular to the axis of rotation.
 5. The rotatable track engaging idler of claim 4 wherein the idler body includes a lesser axial thickness between the inboard surfaces, a medium axial thickness between the outboard surfaces, and a greater axial thickness between the seal protecting wear surfaces. 